Kovar®
Kovar is a nominal 29% nickel, 17% cobalt, 54% iron controlled-expansion alloy. It is widely known for having a coefficient of thermal expansion that matches borosilicate (hard) glasses and alumina ceramics, making it the industry standard for reliable hermetic sealing.
- Forme comuni: Sheet, Strip, Plate, Rod, Wire, Tubing.
- Caratteristiche principali: Matches CTE of Borosilicate Glass & Alumina.
- Application: High-integrity Hermetic Seals (Vacuum Tight).
- Quality: Double melted (VIM-VAR) for inclusion-free microstructure.
Most metals expand much faster than glass when heated. If you try to seal a copper pin into glass, the glass will shatter as it cools. Kovar solves this. Its thermal expansion curve tracks perfectly with "hard" glasses (like Pyrex) and ceramics from -80°C to 450°C, ensuring that the seal remains stress-free and vacuum-tight throughout its life.
Hermetic Sealing
Ensures vacuum-tight seals essential for vacuum tubes, X-ray tubes, and military electronics packages.
Phase Stability
Precise chemistry controls ensure the alloy maintains its austenitic structure down to -80°C, preventing volume changes that could crack seals.
Clean Microstructure
Our Kovar is typically produced via Vacuum Arc Remelting (VAR) to minimize impurities, ensuring uniform etching and plating properties.
| Elemento | Contenuto (%) |
|---|---|
| Nichel (Ni) | 29.0 |
| Cobalto (Co) | 17.0 |
| Ferro (Fe) | Equilibrio |
| Carbonio (C) | 0.02 max |
| Manganese (Mn) | 0.30 |
| Silicio (Si) | 0.20 |
*Note: The specific Nickel-Cobalt-Iron balance is calibrated for precise expansion control.
| Forma del prodotto | Standards (ASTM / AMS / MIL) |
|---|---|
| Bar, Rod, Wire | ASTM F15, AMS I-23011 Class 1, MIL-I-23011 Class 1 |
| Lamiera, striscia, piastra | ASTM F15, AMS I-23011 Class 1, MIL-I-23011 Class 1 |
| Tubing | ASTM F15 |
| DIN Standard | DIN 17745, W.Nr. 1.3981 |
| Temperature Range | Average CTE (µm/m·°C) | Matches |
|---|---|---|
| 30 - 200°C | 5.2 | Hard Glass (Borosilicate) |
| 30 - 300°C | 5.1 | Alumina Ceramics (92% - 99%) |
| 30 - 400°C | 4.9 | Sapphire / Ruby |
| 30 - 450°C | 5.3 | Power Tube Glass |
Power Tubes
Transmitting tubes, traveling wave tubes (TWT), and X-ray tubes requiring vacuum integrity.
Electronic Packages
Transistor outlines (TO headers), hybrid circuit packages, and flat packs.
Scientific Instruments
Feed-throughs for high-vacuum chambers and mass spectrometers.
Lighting
Eyelets and lead wires for high-intensity incandescent lamps.
Need Kovar (ASTM F15) Material?
We maintain a deep inventory of Kovar in plate, sheet, coil, rod, and wire forms. Material is suitable for deep drawing and stamping.
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